Means and method of grinding polygonal articles



April 9, 1957 L. J. LE CLERCQ 2,787,371

I MEANS AND METHOD OF GRINDING POLYSONAL ARTICLES Filed Aug. 1 1954' sShets-Sheet 1 I .1 1 11 I; 28 ,1 v 24 D 19 1? 1 10 INVEN TOR.

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April 9, 1957 L. J. LE CLERCQ MEANS AND METHOD OF GRINDING POLYGONAI.ARTICLES Filed Aug. 16, 1954 lllll,

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ATTOENEM April 9, 1957 J. LE CLERCQ 2,787,871

MEANS AND METHOD OF GRINDING POLYGONAL ARTICLES Filed Aug. 16, 1954 sShets-Sheet 5 IN V EN TOR.

IEON t]: LE CLEQC nited States Patent MEANS AND'METHOD OF GRINDINGPOLYGONAL ARTICLES Leon J. Le Clercq, Glendale, Califi, assignor toGladding, McBean 85' Co., Los Angeles, Calif., a corporation ofCalifornia Application August 16, 1954, Serial No. 449,861

17 Claims. (Cl. 51-110) This invention relates to a method of andapparatus for grinding edge faces of polygonal articles and moreparticularly to a grinding apparatus utilizing the principle ofcenterless grinding and adaptedto automatically position a flatrelatively thin polygonal article such as a tile for grinding of oneedge thereof into precise parallel relation and microdimensioneddistancefrom a plane defined by outermost edge extremities of an opposed edgethereof.

Prior methods and apparatus for grinding polygonal articles such asceramic the have used fixtures or holders for each individual tile. Thefixtures were advanced by conveyer meansin a path which.wasfivertically, laterally and longitudinally nonyielding, to'and'through a grinding zone. The fixtures were spaced apart a precisedistance, and tile were required to befed to said fixtures in precisetimed relation. In such prior apparatus the tilewere required to beaccurately positioned in said fixtures and each tile approached thegrinding zone of the apparatus with an axis disposed parallelto theplaneof the grinding edge face of a grinding 'means and substantiallyaligned with the path of travel of advancement. Obviously such priorgrinding apparatus for such articles demanded careful attention in orderto achieve accurate positioning of each tile in its respective'fixedfixture and often such tile were individually handled. Obviously suchcareful attention and intermittent individual handling of tile requireda slower operation of the grinding apparatus.

This invention contemplates an improved continuously fed grindingapparatus wherein. a plurality of tiles may be successively fed toaconveyer means without regard to longitudinal spacing thereof and whichare automatically properly positioned and supported on the conveyermeans for entry into .and through a grinding zone without the use offixtures for each tile. The invention also contemplates a grindingapparatus wherein the edge face of such a tile may be ground totolerances closer .than those permitted by prior proposed grindingapparatus for this purpose. @The invention employs a centerless grindingprinciple whereby precise .accurategrinding of an edge face of a tileinto parallelism and a preselected accurate microdimensioned distance of minimum tolerance from an opposed edge of a tile may be readily andquickly accomplished so that maximum production may be achieved. 7

It is therefore the primary object of this invention to ,disclose anapparatus for and a method of grinding thin flat polygonal articles intoprecise dimension and with extremely close allowable tolerances.

An object of this invention is to design and provide a grindingapparatus whereineach'tile .is automatically positioned with respect tothe grinding. zoneregardless of its initial position upon beingtransferred to a conveyer means advancing said tile to said, zone.

An object of this invention is to disclose and provide a grindingapparatus wherein the initial position-of tile fed to said apparatus isnot critical.

2,787,87l E'Patent'ed Apr. 9, 1957 Another object of this invention isto disclose and provide a novel improved .grinding apparatus forpolygonal tile wherein guide means are provided for advancing each tileto and through a. grinding zone with the longitudinally disposed axis ofthe tile arranged at an angle to the direaction of its path of traveland to the grinding edge face of grinding means.

Still another object .of this invention is to disclose and provide meanson the grinding apparatus for directing tile against guide means prior.to the grinding zone whereby each tile will be properly positioned'forgrinding.

A further object of this invention is to disclose and provide a grindingapparatus wherein work conveying means is provided with limited lateralyieldability along its length for facilitating positioning of a tile forgrinding.

A still further object of this invention is to disclose and provide agrinding apparatus wherein work conveying means and guide meansfor saidwork are disposed in converging relation and are synchronized inmovement for advancing a tile in proper position to a grinding zone.

Still another object of this invention is to disclose and provide agrinding apparatus wherein flat thin polygonal articles may be supportedand graspedby work conveying means for limiting vertical displacement ofsaid articles and wherein grasping pressure on such articles may beadjustably varied throughout the .length of said means.

Generally speaking this invention contemplates a novel improved methodof and apparatus for grinding edge .faces of flat thin polygonal tilewherein work conveying means is provided to advance said .tile in a pathof travel in a horizontal zone and whereinsaid work conveyer meansincludes opposed spaced parallel conveyer lays movable in the samedirection. One .of said conveyer lays may be variably biased in. thedirection of the other lay. Grinding means including a cup type grindingwheel is adjustably mounted at one side of said conveyer, means foradjustable spacing from said path of travel and is provided with agrinding edge face lying in a plane virtually parallel to said path oftravel. vLongitudinally extending. guide means are provided on theopposite side of. the conveyer means and may include an endless metalband having an inboard" lay disposed at an angle to said path of traveland converging therewith, said inboard lay being movable in the samedirection and at virtually'the same rate of speed as the opposed workconveyer lays.

Means are provided at the feed end of the conveyer means for directingtile against said inboard lay of the guide means whereby said tile willbe advanced to and through a grinding zone of predimensioned width asdefined by said grinding edge face and anintermediate opposed portion ofsaid inboard guide lay for precise grinding of one edge face of saidtile.

Other objects and advantages of this invention will be readily apparentfrom the following description of the drawings in which an exemplaryembodiment of this invention is shown.

In the drawings:

Fig. 1 is a diagrammatic view of a grinding apparatus embodying thisinvention showing its arrangement in a production line.

Fig. 2 is a top view of a tile to be ground by the apparatus of thisinvention.

Fig. 3 is a top view of the grinding apparatus embodying this invention.

Fig. 4 is an elevational view of the apparatus shown in Fig. 3, theelevation being takenin the plane indicated by line IVIV of Fig. 3.

Fig. 5 is a fragmentary sidegelevational view taken in the planeindicated by line VV of Fig. 3.

Fig. 6 is an end view taken from the right of Fig. 3.

this invention, a flat polygonal article such as a tile in Fig. 2 isillustrative of an article which may be ground with parallel edgeextremities into precise dimension. Exemplary tile 10 is provided withpairs of opposed edge faces 11 and 12, each edge face 12 being providedwith a plurality of tile-spacing elements 13 unsymmetrically and.

nonuniformly arranged with respect to the axes of said tile. Theelements 13 have outermost edge extremities which define a plane. Oneelement 13 may be disposed in 1 close proximity to one end of edge face12. It is desired that opposed edge face 11 which may be plain anduninterrupted be made precisely parallel to said plane and be preciselydimensioneda preselected distance from said plane. Such a tile isdescribed and claimed in co-pending applications Serial No. 391,979 andSerial No. 310,659. Such a tile with precisely dimensioned outermostextremities in precise parallelism affords tile which may be installedrapidly in a pattern wherein courses of said tile may be accurately laidso that opposed planes of edge extremities are precisely parallel andspaced apart and thus provide uniform joint lines between said tile.

In general, such tile 10 may be pressed oversize so that the edge faces11 may be ground to precise dimension.

In Fig. 1 a line of tile 10 inabutment may be continuously fed to agrinding apparatus 15 embodying this invention by a suitable feedconveyer 16 moving at a' preselected speed. At apparatus 15 the tile arelongitudinally spaced by a grinder conveyer means 17 which receives thetile and which moves at a rate of speed greater than feed conveyer 16.On the grinder conveyer 17 the tile are passed through a grinding zone Gand through a fettling zone F. After discharge from the fettling zone F,the tile are turned 90 and then fed to a second similar grindingapparatus 15 for grinding the other edge face 11. The tile dischargedfrom the second grinding apparatus 15 may be stacked and handled in anywell-known suitable manner.

The grinding apparatus 15 embodying this invention comprises in additionto the grinder conveyer 17, grinding means 19 and a fettling means 20 atone side of the grinder conveyer 17, and a work guide means 21 at theother side of the grinder conveyer 17. The several means 17, 19, 20 and21 may be supported by a frame structure 22 fragmentarily shown andwhich may comprise any well-known construction.

The grinder conveyer 17 may comprise top and bottom endless belt means24 and 25 having opposed lays movable in the same direction and speed,the top belt means extending through the grinding zone G and the bottombelt means through both the grinding and fettling zones. The bottom beltmeans 25 serves to define a longitudinal path of travel for a tilethrough the grinding apparatus 15. The belt means 25 may comprise a pairof laterally spaced parallelendless flexible V-belts 26 supported attheir ends by pairs of end pulleys 27 and 28. End pulley 27 may becarried by a shaft journaled in an upstanding member 29 (Fig. 6) securedto a transverse plate 30 provided on spaced longitudinal angle beams 31.End pulleys 28 (Fig. 7) may be carried on a shaft 32 journaled in ablock 33 supported from beams 31 by a plate 34, shim 35 and alongitudinal bar 36. Longitudinal bar 36 may be supported at its otherend by means later described. Pulleys 28 may be connected to drivingmeans (not shown) in any suitable manner.

In the approach to and in the grinding zone G the top lays of belts 25are supported for movement in a selected relatively unyieldinghorizontal plane by a plurality of pairs of longitudinally spaced pulleywheel assemblies 38. Each assembly 38 (Fig. 8) includes a shaft bottombelt means. means is slightly inclined to the path of travel of the tile39 journaled by suitable bearing means 40 in a longitudinal member 41.The longitudinal member 41 is secured at one end to the upstandingmember 29 by suitable stud bolts 42 and at the other end to anupstanding member 43 positioned between the ends of the belt means andapproximately opposite the end of the grinding zone. Upstanding member43 is supported on a plate 44 carried by beams 31 and serves also tosupport the inner end of longitudinal bar 36. It should be noted that inthe approach to the grinding zone the spacing of assemblies 38 isrelatively great, while in the grinding zone the assemblies 38 arespaced apart a minimum distance to accurately support movement of a tilealong its path.

Means for tightening endless belts 26 may be conveniently provided bymovable tightening wheels 46 carried by a supporting element 47pivotally mounted at 48 to the upstanding member 29. A threaded bolt 49and a lock. nut 50 serve to adjust the wheels 46. A second adjustingpulley 51 may be mounted on a shaft 52 movable vertically in parallelslots 53 provided in the upstanding member 43 by a suitable wedge 54aactuated by a longitudinally movable block 54 slidable in a slotprovided in longitudinal bar 36.

In the fettling zone F (Fig. 9) the top lay of the endless belts 26 maybe supported by a plurality of vertically spring-biased movable wheelassemblies 56. Each assembly 56 includes a transverse shaft 57antifrictionally mounted in a block 58. The block 58 is provided withslots 59 on opposite sides thereof which slidably receive pins 60. Thepins 60 may be carried by spaced parallel side plates 61 which areconnected at their bottom portions to the longitudinal bar 36 bysuitable stud bolts 62. Each block 58 is spring-biased upwardly by meansof a coil spring 63 received within a downwardly opening recess 64provided in the bottom portion of block 58. The

upper end of the spring 63 is seated against a washer carried by bolt 67in recess 64. The other end of the spring may be seated against anadjustable insert 65 which is threadedly received within a port 66 inthe bar 36. The insert 65 is ported to receive securing bolt 67 whichextends through the insert and which may be provided with a threaded endfor threaded engagement with the block 58. The insert 65 may beadjustably set so that the compression of spring 63 may be varied.

The top endless belt means 24 of the grinder conveyer 17 comprises apair of laterally spaced parallel endless V-belts 70 carried by pairs ofend pulleys 71 and 72. The

I end pulleys 71 are supported by a transverse shaft 71a which may bejournaled in suitable manner in a depending longitudinally adjustablesupporting block 73 having an upper reduced end portion passing througha longi' tudinally aligned slot 75 in bar 74. Suitable securing means 76may be provided to position the upper end portion of the supportingblock 73 within the slot. The other end pulleys 72 may be carried by atransverse shaft 77 antifrictionally mounted in a suitable supportingblock 78 which may be fixed by suitable stud bolts 79 to the rigid bar74.

Means for supporting the top belt means 24 in selected position over thebottom belt means 25 may comprise a pair of transverse, longitudinallyspaced frame members 81, each provided with a pair of transverse slots82 open at the end of members 81. The slots 82 receive securing studbolt assemblies 83 for supporting the longitudinal bar 74. The slots 82permit adjustment of the top belt means 24 laterally of the apparatusand at a selected angle to the axis of the path of travel of tilecarried by the Preferably, the axis of the top belt and convergestherewith at the grinding zone.

The bottom lays of the endless top. belts 70 are guided by a pluralityof vertically adjustable, downwardly springbiased, closely spaced pulleywheel assemblies 85. Each wheel assembly 85 (Fig. 8) includes atransverse shaft 86 carried in a vertically adjustable block 87.Opposite sides of block 87 are provided with vertically extending slots88 which receive: pins 89 carried by longitudinal side plates 90 which.may be secured to longitudinal bar 74 by stud bolts 91. Each block 87 isprovided with an upwardly opening recess 92 terminating in a threadedbore 93 for receiving a threaded end portion of a securing bolt 94.Sleeved over bolt 94 and within the recess 92 is a coil spring 95 placedunder compression between a spring seat 96 carried by the bolt and atension-adjusting insert 97 threadedly carried in a bore provided in bar74. The insert 97 has a port through which bolt 94 passes. It should benoted that each assembly 85 is opposed to an assembly 38 provided on thebottom endless belt means 25. The downwardly biased assembly 85 iscooperable With the n'onyielding assembly 38 to resiliently hold andposition a tile therebetween as the tile passes through the grindingzone.

Means for guiding the top lays of endless belts 70 may comprise a pairof fixed pulley wheels 100 adjacent the end pulley wheels 71 and engagedwith the top lay of belts 70. A longitudinally adjustable pulley wheelassembly 101 may be carried by a transverse shaft 102 positioned withina longitudinally extending slot 103 provided in block 78. Longitudinalmovement of the pulleys 101 exerts pressure against the top lays of theendless belts 70 to tighten and to take up any undesired slack in saidbelt means. Suitable means may secure the pulleys 101 in selectedposition.

In the fettling zone, the longitudinal bar 74 extends over the upwardly,yieldably biased assemblies 56 of the bottom belt means and may carry asuitable structural member 105 having secured thereto longitudinal anglemembers 106 withdepending flanges 106a (Fig. 7). The flanges 106a may beprovided with a plurality of longitudinally spaced aligned ports forreceiving transverse shafts 107 which support a plurality of rollers 108above the assemblies 56. The nonyieldable rollers 108 cooperate with theyieldable upwardly biased assemblies 56 to resiliently grip a tile as itis passed through the fettling zone.

The grinding means 19 may be disposed to one side of the grinderconveyer means 17 and may include a single cup-type grinding wheel 110mounted for rotation about a horizontal axis perpendicular to the pathof travel of a tile defined by the grinder conveyer 17. The grindingwheel 110 is provided with an annular grinding edge face 111 (Figs. 1and 8) which lies in a plane virtually parallel to said path of travel.The grinding wheel 110 may be driven by suitable motor means (not'shown)carried by the frame structure 22. bodiment of this invention thegrinding wheel 110 may be fixedly and rigidly mounted, but it isunderstood that said grinding wheel may be-adjustably mounted so as tomove the grinding edge face 111 toward and away from the path of travelof the tile if so desired. A cover guard 112 may be provided for thegrinding wheel.

At the other side of the grinder conveyer 17 the guide means 21 may besuitably adjustably supported from the frame structure 22 (Figs. 1, 5, 6and 7). The guide means 21 may comprise a pair of longitudinally spacedhorizontally disposed pulley wheels 114 mounted for rotation aboutvertical axes provided by vertical shafts 115. One of said wheels 114 islocated opposite the feed end of the bottom endless belt means 25 andthe other pulley wheel 114 is located at the discharge end thereof. Thepulley wheels 114 support, and drive through suitable means (not shown),an endless thin flat metal band 116 which provides an inboard lay 117having an inboard guide face 118 lying in a vertical plane and in thesame horizontal plane as the path of tile through the grindingapparatus. The inboard lay 117 may be supported throughout its lengthagainst lateral yieldability by a suitable rigid guide bar 119 supportedfrom a longitudinally extending plate 120 which may carry journals forthe wheel shafts 115.

In the exemplary em- The work guide means 21 (Fig. 1) also comprises abottom longitudinal plate 121 and verticalrnembers .122, 123, and 124which support the longitudinal plate thereabove. The bottom plate 121 isadjustably mounted on the transverse plates 30 carried by the frameangle members 31 by suitable bolt and nut assemblies 126, said bolt andnut assemblies being received within transversely disposed slots 127provided in the transverse members 30.

It will thus be apparent that the entire work guide means 21 may bemoved laterally with respect to the conveyer 17 and may thus positionthe inboard guide face 118 of the metal band at a selected distance fromthe grinding wheel so as to accommodate tile of different width. Theadjustable mounting of the work guide means 21 also permits the guidemeans to be adjusted into a selected angular relationship to the path oftravel of the tile and to precisely determine the dimension to which thetile are to be ground. This precisev dimension is determined by thespacing of the inboard face 118 from the last edge ofcontact of theannular grinding edge face 111 with a tile as indicated atD (Fig. 1 Theinboard face 118 is disposed so as to converge to this criticaldimension and to thereby guide and position tile for precise grinding.

It may also be noted that the inboard guide face 118 is supportedopposite the fettling zone so that in the fettling operation the tile isproperly positioned for providing a suitable bevel on the edges thereof.

At the feed end of the grinder conveyer 1 7 suitable means may beprovided for directing tile received thereat toward and against theinboard guide face 118 of metal band 116. Such. means may comprise anangularly disposed member 128 carried by the frame stntcture 22. Themember 128 provides a smooth flat inboard surface which may extend intoclose proximity with the bottom belt means 25. for positively urging atile thereacross into contact with the metal band.

In the apparatus of this invention described above it will be understoodthat suitable synchronized drive means may be provided for driving thetop and bottom endless belt means 24 and 25 and the work guide metalband 116 at the same speed. The drive means do not form a part of thisinvention and are therefore not described.

At the fettling zone F a plurality of suitable fettling grinding units129 may be mounted. Each provides a downwardly biased, freely rotatablegrinding disc 130 positioned at a selected angle and carried by a shaft131. The shaft 131 may be mounted in a hollow, cylindrical housing 132suitably secured to the top longitudinal bar 74. Within the housing acoil spring (not shown) actingbetween the housing and a spring seatassociated with shaft 131 biases the shaft downwardly in well knownmanner. The grinding disc 130 is disposed so as to bevel the top edge ofa ground edge face of a tile presented thereto as the tile is movedalong its path by the grinder conveyer 17. The construction of thefettling units does not form part of this invention and is not describedin detail.

In operation of the grinding apparatus of this invention a. plurality oftiles or articles to be ground may be continuously fed to the grinderconveyer 17 by means of any suitable feed conveyer 16. Tile arepositioned on the feed conveyer with an edge face to be ground disposedlongitudinally and facing the side on which the grinder means 19 ispositioned. As the tile are advanced and trans ferred to the grinderconveyer 17, the tile are automatically spaced apart a selected distanceby the greater rate of speed of travel of the grinder conveyer 17 ascompared to the speed of travel of the feed conveyer. As the tile areadvanced by the bottom belt means 25 of the grinder conveyer 17, eachtile is initially urged laterally toward the work guide means 21 by theangularly disposed member 128. Thus, the leading corner of the guideface 118 of the metal band 116.

As a tile advances between the opposed lays of the top and bottom beltmeans 24 and 25, the angular disposition of the top belt means withrespect to the bottom belt means causes the edge face or edgeextremities of the edge of the tile opposite to the edge to be ground tobe urged against the inboard guide face 118 for the entire length. ofthe edge of the tile. The tile is thus positioned with its longitudinalaxis disposed angularly with respect to the longitudinal axis of thebottom belt means which is serving to define a path of travel for thetile. In this manner, each tile is advanced toward the grinding zone andis so positively positioned against the inboard guide face 118 of themetal guide band that it will readily pass by the annular grinding edgeface 111 nearest to the feed end of the conveyer 17.

As each tile advances through the grinding zone, the angular inclinationof the top belt means continues to position each tile with itslongitudinal axis parallel to the inboard guide face 118 of the metalguide band by urging edge extremities of the tile against said guideface. In addition, each tile is resiliently gripped between the opposedlays of the top and bottom belt means and is fioatably held thereby. Itmust be remembered that the top and bottom belt means are provided withflexible V-belts and that the lower lay of the top belt means isdownwardly biased under a selected biasing pressure by the pulley wheelassemblies 38.

The grinding wheel 110 is rotated so that the grinding edge face 111 ismoved downwardly on the side remote from the feed end of the conveyer17. As each tile comes into contact with the grinding edge face 111,static pressure developed urges the tile firmly against the inboardguide face 118, the flexible belt means permitting limited movementthereof. The spacing of the last grinding edge element directly oppositefrom the inboard guide face 118 is preselected and readily achieved byproper positioning of the work guide means and the grinding wheel. Thus,as each tile engages the grinding wheel, the edge face of the tile to beground will be precisely parallel to the plane of the edge extremitiesof the opposite side of the tile in contact with the work guide face118.

Each tile continues along the bottom belt means with one edge in contactwith the inboard guide face 118 as it passes through the fettling zone.In the fettling zone the grinding discs 130 are suitably positioned sothat the sharp top edge resulting from grinding of the tile is cut awayto provide a beveled top edge corresponding to the nonground top edgesof the tile. After each tile is discharged from the fettling zone it maybe turned 90 in a well-known manner to position the other edge face tobe ground for grinding in a second grinding apparatus of .the sameconstruction and operation as that described above.

It will thus be understood by those skilled in the art that a novelapparatus and method for grinding edge faces of articles has beendescribed above wherein essential features of centerless grinding areutilized. Thus, a precise, accurately dimensioned tile is achieved bythis apparatus and method which when installed in a pattern will provideuniform parallel courses with unitform joint lines wherein care andskill required to install the tile is reduced to a minimum.

It wiil also be understood that while the apparatus has been describedfor use with an exemplary ceramic tile, other articles of differentmaterial may be readily ground to precise dimension with parallel edgefaces by the apparatus and method of this invention.

Numerous modifications and changes may be made which come within thespirit of this invention and all such changes and modifications withinthe scope of the appended claims are embraced thereby.

I claim: 1. In an apparatus for grinding an. edge face of an articleinto precise parallel andmicrodimensioned distance from a planedetermined by opposite edge extrcmities of said article comprising, incombination: a conveyer means for advancing a plurality of articlessuccessively along a predetermined horizontal path at a preselected rateof speed, said conveyer means including spaced apart opposed laysadapted to move in the same direction, said lays being adapted toresiliently grip an article therebetween and having limited lateralmovement; a grinding means at one side of the conveyer means includingan annular grinding edge face disposed in a vertical plane facing saidpath; a longitudinally extending guide means at the other side of saidconveyer means, said guide means comprising an endless metal band havingan inboard lay provided with an inboard edge face lying in a verticalplane convergent to said path, a rigid guide bar supporting saidvertical inboard lay; positioning means adjacent said grinding means andthe feed end of said conveyer means and extending inboardly of the planedefined by said annular grinding edge face for cooperation with theopposed end of said guide means for causing an article advanced on saidconveyer means to become disposed with its axis angularly related tosaid path and parallel to the inboard edge face of said guide means;said guide means defining with a portion of said annular grinding edgeface a grinding zone of predetermined microdimensioned width wherebyarticles advanced along said conveyer means and guided by said guidemeans are passed through said grinding zone with their axes at an angleto the path of travel.

2. An apparatus as stated in claim 1 wherein said guide means extendsbeyond said grinding zone in said direction of advancement.

3. An apparatus as stated in claim 1 wherein said guide means isadjustably mounted for movement towards and away from said path oftravel for precisely spacing the inboard face of the inboard lay of saidmetal band from said grinding means.

4. In an apparatus for grinding edge faces of articles into preciselyparallel and microdimensioncd spaced relationship the combination of: aconveyer for advancing articles to be ground along a predeterminedhorizontal path at a preselected rate of speed and including means forlimiting vertical displacement of said articles from said path, saidlimiting means being disposed at an angle to said path; a grinding meansat one side of the conveyer means provided with a vertically disposedgrinding edge face; a longitudinally extending guide means on theopposite side of the conveyer means comprising an endless belt having aninboard horizontal lay with a vertical inboard face, said verticalinboard face lying in a plane convergent to said path, said inboard faceof said inboard lay intermediate its ends beingspaced apart apredetermined distance from the grinding edge face of said grindingmeans to define a grinding zone; and means at the feed end of saidconveyor means to direct an article fed to said conveyer means againstsaid inboard lay of said guide means.

5. In an apparatus as stated in claim 4 wherein said endless belt ofsaid guide means is adapted to be driven in synchronism with saidconveyer means whereby said inboard lay is advanced at the same rate ofspeed as edge face lying in a second plane facing one side of said path;guide means opposite to said grinding means and presenting a guide facelying in a third plane disposed at an angle to said path and inconverging relation thereto, said planes of said guide face and saidgrinding edge facedefining a grinding zone of predetermined dimension;means at the feed end of said conveyer means to direct a tile fed tosaid conveyer means against said guide face prior to said grinding zonewhereby a leading corner of a tile is positioned in contact with saidguide face.

8. In a grinding apparatus as defined in claim 7 wherein said guide faceis adapted to be movable at a rate of speed virtually the same as thespeed of the conveyer means.

9. In a grinding apparatus as defined in claim 7 wherein said conveyermeans includes a pair of spaced lays adapted to move in the samedirection at the same speed, one of said lays being virtuallynonyieldable in a vertical direction and the other of said lays beingvariably biased toward the other lay throughout its length for yieldablylimiting vertical displacement of said tile.

10. A grinding apparatus as defined in claim 9 wherein each of said laysof said conveyer means are limitedly laterally movable adjacent saidgrinding zone for floatingly aligning said tile with said grinding zone.

ll. A grinding apparatus as defined in claim 9 wherein one of said laysis disposed at an angle to said path to positively Urge and hold a tilein contact with said guide face.

12. In a grinding apparatus for grinding opposite faces of an articleprecisely parallel, the combination of: a grinding means including anannular grinding edge face rotatable in a plane; a work guide meanshaving a guide face inclined to said plane, said guide face being spaceda preselected distance from said grinding edge face in a grinding zoneand adapted to be contacted by an article being ground; and conveyermeans for advancing an article through the grinding zone and comprisingtop and bottom belt means having opposed lays adapted to resilientlygrip and position said article against said guide face in the approachto and in the passage through said grinding zone.

13. In a grinding apparatus as defined in claim 12 wherein thelongitudinal axis of one of said belt means is angularly disposed to thelongitudinal axis of the other belt means.

14. In a grinding apparatus as defined in claim 12 wherein said guideface extends beyond said grinding zone; and fettling means are providedopposite said extension in transverse spaced relation thereto forgrinding an edge of an article ground in the grinding zone.

15. In a grinding apparatus for grinding a face of an article preciselyparallel to an opposite face, the combination of: a grinding meansincluding a grinding edge face lying in a vertical plane; a work guidemeans spaced from said grinding means and providing a vertical guideface inclined to said plane and spaced a preselected distance from saidplane at a grinding zone; conveyer means between said guide face andsaid grinding edge face for advancing an article through the grindingzone, said conveyer means including a horizontal belt means having itslongitudinal axis extending generally parallel to the plane of thegrinding edge face and a second belt means spaced from and cooperablewith the first belt means for gripping an article to be ground duringadvancement into and through the grinding zone, said second belt meanshaving an axis angularly disposed to the plane of said grinding edgeface whereby said second belt means is adapted to urge and hold anarticle being ground against said guide face.

16. In a grinding apparatus, the combination of: a conveyor means foradvancing successively at a selected rate of speed, articles to beground along a predetermined path lying in a first plane; grinding meansat one side of said path provided with a grinding edge face lying in asecond plane perpendicular to the first plane and facing said path;guide means opposite to said grinding means and provided with alongitudinally extending guide face lying in a third plane perpendicularto said first plane and converging in angular relation to said secondplane in the direction of advancement of said articles, said guide facebeing spaced from said grinding edge face at a grinding zone, said guideface extending beyond said grinding zone and continuing to be disposedin convergent re'lat-ion to said second plane.

17. A method of grinding an edge face of a fiat polygonal articleprecisely parallel to an opposite edge face, comprising the steps of:rotating a grinding face in a plane at .a grinding zone; advancing suchan article with an edge face opposite to the edge face to be groundlying in a plane inclined to the plane of said grinding face;

supporting the edge face opposite to the edge face to References Citedin the file of this patent UNITED STATES PATENTS 188,569 Beers Mar. 20,1877 920,859 Gardner May 4, 1909 2,038,150 Weber Apr. 21, 1936 2,263,897

Makenny Nov. 25, 1941

